The impact of agricultural management on selected soil properties in citrus orchards in Eastern Spain: A comparison between conventional and organic citrus orchards with drip and flood irrigation. , 581, 153-160.

The agricultural management of citrus orchards is changing from flood irrigated managed orchards to drip irrigated organic managed orchards. Eastern Spain is the oldest and largest European producer of citrus, and is representative of the environmental changes triggered by innovations in orchard management. In order to determine the impact of land management on different soil quality parameters, twelve citrus orchards sites were selectedwith different land and irrigation management techniques. Soil samples were taken at two depths, 0-2 cmand 5-10 cm for studying soil quality parameters under the different treatments. Half of the studied orchardswere organicallymanaged and the other sixwere conventionally managed, and for each of these six study sites three fields were flood irrigated plots and the other three drip irrigated systems. The outcome of the studied parameters was that soil organic matter (SOM) and aggregate stability were higher for organic farms. Bulk density and pH were only significantly different for organic farms when drip irrigation was applied in comparison with flooded plots. C/N ratio did not vary significantly for the four treatments. Although there are some points of discussion, this research shows that a combination of different management decisions leads to improvement of a couple of soil quality parameters. Organic management practiceswere found to be beneficial for soil quality, compared to conventional management for soils with comparable textures and applied irrigation water

Soil rehabilitation in semi-arid Spain: Long-term effect of afforestation and land abandonment on soil quality

In response to the increasing amount of abandoned agricultural land in the European Mediterranean area during the last century, afforestation projects have been conducted as a measure for soil protection and ecosystem restoration. Despite the research on the impact and effectiveness of these projects, the long-term effect on soil quality has hardly been studied. Especially the linkage between soil physical, chemical and hydrological properties is lacking. An intensive fieldwork has been carried out in Murcia, southeastern Spain to study the effects of land abandonment and afforestation on soil quality along a chronosequence and included two afforested areas, planted with Pinus halepensis trees in the early ‘70s and ‘90s. Samples were taken to study changes in soil physical and chemical quality (e.g. Aggregate stability, Corg, N, P, K, Na), Soil Organic Carbon (SOC) stocks and soil hydrological properties, such as infiltration and water retention. A comparison was made between afforestation projects, abandoned agricultural plots of similar age, semi-natural vegetation and cereal crop fields. As the natural vegetation is characterized by a spotted pattern of bare areas and trees, forming so-called “islands of fertility”, both bare and vegetation covered sub-sites were included. Our results indicated that under secondary succession on abandoned fields, soil quality showed a marginal non-linear improvement over the studied period. The afforestation showed a much more pronounced linear increase, resulting in a soil quality comparable to what can be found under semi-natural vegetation. After 40 years afforestation showed to be successful in the restoration of the natural soil hydrological functioning, while the abandoned sites only indicated small changes. For this case study, in semiarid areas, afforesting is the best way forward as it has a clear effect on enhancing soil quality compared to secondary succession on abandoned agricultural fields

Eco- and Ground Bio-engineering: the Use of Vegetation to Improve Slope Stability: Proceedings of the First International Conference on Eco-engineering 13-17 September 2004

O-07-01In an era where climate change, natural catastrophes and land degradation are major issues, the conservation of soil and vegetation in mountainous or sloping regions has become an international priority. How to avoid substrate mass movement through landslides and erosion using sustainable and ecologically sound techniques is rapidly becoming a scientific domain where knowledge from many different fields is required. These proceedings bring together papers from geotechnical and civil engineers, biologists, ecologists and foresters, who discuss current problems in slope stability research, and how to address those problems using ground bio- and eco-engineering techniques. Ground bioengineering methods integrate civil engineering techniques with natural materials to obtain fast, effective and economic methods of protecting, restoring and maintaining the environment whereas eco-engineering has been defined as a long-term ecological strategy to manage a site with regard to natural or man-made hazards. Studies on slope instability, erosion, soil hydrology, mountain ecology, land use and restoration and how to mitigate these problems using vegetation are presented by both scientists and practitioners. Papers encompass many aspects of this multidisciplinary subject, including the mechanisms and modelling of root reinforcement and the development of decision support systems, areas where significant advances have been made in recent years

The fate of soil organic carbon upon erosion, transport and deposition in agricultural landscapes - A review of different concepts

Erosion and deposition redistribute large quantities of sediment and soil organic carbon (SOC) in agricultural landscapes. In the perspective of global carbon cycling, the coupling between erosion processes and the fate of SOC is of particular interest. However, different concepts have been proposed to assess the impact of erosion-induced lateral and vertical carbon fluxes. On landscape scale, this resulted in contrasting conclusions if agricultural soils represent either a carbon sink or source. The large global area of arable soil and generally high erosion rates, make these insights important. In this review, we aim to give an overview of the different conceptual relations described governing C dynamics at sites of erosion, along the transport pathway and at depositional sites and the current state of knowledge on the fate of SOC upon erosion, transport and deposition in agricultural landscapes.The impact of erosion on SOC dynamics differs for sites of erosion, deposition and during transport, with further influences by agricultural practices (e.g. tillage and fertilisation). Controlling processes are the detachment of sediment and SOC, net primary production resulting in dynamic replacement and changes in mineralisation upon transport and deposition due to aggregate breakdown and deep burial, respectively. However, the exact magnitude and dominance of these processes are debated, resulting in a controversy whether arable land functions as a sink or source for atmospheric CO2. Global estimations range between a net sink strength of 0.06-1 versus a source of 0.27-1.14GtCyr-1 for agricultural soils.An eco-geomorphologic approach, which encompasses physical- and biological-driven factors (e.g. spatio-temporal variation in biological, geomorphological and biological processes, environmental conditions, mineralisation, and net primary production) is of importance to balance the carbon budget and ascertain sink or source formation at landscape scale. High spatio-temporal variability on process-scale imposes constrains, to measure and model the fate of SOC upon erosion, with limited quantitative data available. Prospective research across the landscape (eroding sites, transport pathway, and depositional sites) should include all relevant processes at broad temporal and spatial scales. Definitive resolution of the sink/source controversy lies in further eco-geomorphologic research on the fate of SOC, focussing on long-term and spatial extensive monitoring studies, combined with advanced measuring, modelling and extrapolation techniques to cover broad spatio-temporal SOC dynamics. Ascertainment of carbon dynamics in agricultural landscapes provides important insights to balance the carbon budget and finally holds the answer on sink/source formation

The fate of soil organic carbon upon erosion, transport and deposition in agricultural landscapes - A review of different concepts

Erosion and deposition redistribute large quantities of sediment and soil organic carbon (SOC) in agricultural landscapes. In the perspective of global carbon cycling, the coupling between erosion processes and the fate of SOC is of particular interest. However, different concepts have been proposed to assess the impact of erosion-induced lateral and vertical carbon fluxes. On landscape scale, this resulted in contrasting conclusions if agricultural soils represent either a carbon sink or source. The large global area of arable soil and generally high erosion rates, make these insights important. In this review, we aim to give an overview of the different conceptual relations described governing C dynamics at sites of erosion, along the transport pathway and at depositional sites and the current state of knowledge on the fate of SOC upon erosion, transport and deposition in agricultural landscapes.The impact of erosion on SOC dynamics differs for sites of erosion, deposition and during transport, with further influences by agricultural practices (e.g. tillage and fertilisation). Controlling processes are the detachment of sediment and SOC, net primary production resulting in dynamic replacement and changes in mineralisation upon transport and deposition due to aggregate breakdown and deep burial, respectively. However, the exact magnitude and dominance of these processes are debated, resulting in a controversy whether arable land functions as a sink or source for atmospheric CO2. Global estimations range between a net sink strength of 0.06-1 versus a source of 0.27-1.14GtCyr-1 for agricultural soils.An eco-geomorphologic approach, which encompasses physical- and biological-driven factors (e.g. spatio-temporal variation in biological, geomorphological and biological processes, environmental conditions, mineralisation, and net primary production) is of importance to balance the carbon budget and ascertain sink or source formation at landscape scale. High spatio-temporal variability on process-scale imposes constrains, to measure and model the fate of SOC upon erosion, with limited quantitative data available. Prospective research across the landscape (eroding sites, transport pathway, and depositional sites) should include all relevant processes at broad temporal and spatial scales. Definitive resolution of the sink/source controversy lies in further eco-geomorphologic research on the fate of SOC, focussing on long-term and spatial extensive monitoring studies, combined with advanced measuring, modelling and extrapolation techniques to cover broad spatio-temporal SOC dynamics. Ascertainment of carbon dynamics in agricultural landscapes provides important insights to balance the carbon budget and finally holds the answer on sink/source formation

Development of spatial heterogeneity in vegetation and soil properties after land abandonment in a semi-arid ecosystem

To mitigate erosion on abandoned fields in semi-arid ecosystems, it is important to understand how vegetation and soil properties and patterns develop after land abandonment. Our objective was to investigate the development of spatial heterogeneity in vegetation and soil properties after land abandonment. We described the vegetation composition, collected soil samples and made detailed aerial photographs for two series of abandoned fields on marl and calcrete in Southeast Spain. The images were classified into bare and vegetated patches, and spatial metrics were calculated for each site. Our results showed that recovery of vegetation and change in soil properties after land abandonment are slow and take at least 40 years in such a semi-arid enviromnent. Succession on calcrete appeared to be faster than on mad, probably because more water is available due to the higher rock fragment cover. Organic matter, aggregate stability and electrical conductivity were all significantly higher under vegetated patches, We found a clear linear relationship between vegetation cover and most spatial metrics, which offers the possibility of upscaling spotted vegetation patterns. The results of our integrated approach to study spatial heterogeneity in vegetation and soil properties can be used to improve predictions of runoff and erosion. (c) 2008 Elsevier Ltd. All rights reserved

Soil and organic carbon redistribution in a recently burned Mediterranean hillslope affected by water erosion processes

Forest fires cause many changes in the physical, chemical and biological soil properties such as aggregation and soil organic carbon contents (SOC) as well as on soil hydrology and erosion processes. Most studies on post-fire soil erosion in Mediterranean environments have been plot-based and research at hillslope or broader scale is scarce. Understanding SOC nature, distribution and modifications, as produced by forest fires and erosion, has become crucial to model and define the role of soil erosion as source or sink of C, and to sustainably manage ecosystem services related to the soil resource. This research provides data about the loss and redistribution of soil and SOC in a Mediterranean forest hillslope burned with high severity, at the Natural Park of Sierra de Espadán, Spain. Soil was sampled in coupled hillslopes (ca. 0.25 ha) (BU: burned, CO: control) at bottom (depositional), middle (transport) and top positions (eroding) at two depths (0-2 cm, 2-5 cm), and under two environments (UC: under canopy soil, BS: bare soil). Sediments were collected after each erosive event along one year, and yields were calculated. Samples were analysed to assess aggregate stability (AS), size and density fractionations, SOC contents and stocks. The main hypothesis is that fire affects soil characteristics related to aggregation and SOC stabilization and, together with erosion processes, may modify SOC distribution within aggregates and the burned hillslope